Patent Document 1 discloses novel carboxybetaine-type amphoteric surfactants. When hair-treatment compositions containing such amphoteric surfactants are used on dyed keratin fibers, they exhibit a color-retaining effect, that is, a color fade suppressing effect, on the dyed keratin fibers. Examples of the amphoteric surfactants disclosed in Patent Document 1 include C12-14 hydroxyalkyl hydroxyethyl sarcosine.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-22085